Rear suspensions have become commonplace in off-road bicycles such as mountain bikes. Rear suspensions allow the rear wheel to pivot upward relative to a forward portion of the bicycle frame to damp and absorb the impact of off-road features such as rocks commonly found on mountain biking trails. Such rear suspension frames typically include a rigid front frame portion pivotally connected to a rear frame portion functioning as a swing arm pivoting about a pivot or pivots between the front frame portion and the rear frame portion. Typically a spring or shock absorber is connected between the front frame portion and the rear frame portion to bias the rear frame portion to a rest or un-pivoted position relative to the front frame portion and to absorb or damp pivoting of the rear frame portion about the pivot(s) as an obstacle is encountered. One known problem with many rear suspension systems is that as a rider pedals, the shifting of the rider's weight and variations in chain force causes the suspension to bob, a condition commonly known as “pedal bob”, wasting rider energy and potentially causing a loss of traction for the rear wheel. In an effort to minimize pedal bob, a variety of bicycle frame rear suspensions have been devised, many of which incorporate a number of pivots and links. These various bicycle frame rear suspensions have varying success in minimizing pedal bob while maintaining pedaling efficiency. However, the additional pivots and links these rear suspensions require add weight and cost to the bicycle frame and create maintenance issues as invariably grit invades the pivots creating annoying creaks and increasing wear of the pivots. Thus, a need exists for a bicycle rear suspension frame which reduces pedal bob and maintains pedaling efficiency while reducing the number of links and pivots in the rear suspension.
The present invention is directed toward overcoming one or more of the problems discussed above.